Probably not comprehensive, and in no particular order...
| feature name | example | include? |
|---|---|---|
| string interpolation | “a#{b}” | Y |
| assignment | a = b | Y |
| single-line comment | # comment | Y |
| integer literal | 1 | Y |
| decimal literal | 1.1 | Y |
| boolean literal | true/false | Y |
| parentheses for grouping | (a or b) and c | Y |
| logical operators | and/or/not/&&/||/! | Y |
| comparison operators | />=/==/!=/is/isnt | Y |
| member access | a.b | Y |
| dynamic member access | a[b] | Y |
| explicit function application | a(b, c) | Y |
| indentation introduces blocks | if a <\n> <indent> b | Y |
| `then` introduces block | if a then b | Y |
| @-vars | @a | Y |
| unary existential operator | a? | Y |
| conditional execution | if a then b | Y |
| conditional else clause | if a then b else c | Y |
| negated flow control keywords | unless/until | Y |
| in operator | a in b | Y |
| of operator | a of b | Y |
| instanceof operator | a instanceof b | Y |
| negated infix operators | not in, not of, not instanceof | Y |
| for-in | for v, k in a then e | Y |
| for-of | for k, v of o then e | Y |
| filtered loops via when | for a in b when c then d | Y |
| own keyword for hasOwnProperty filter | for own k of o then c | Y |
| single-line function literals | (a, b) -> c | Y |
| parameter-less functions | -> a | Y |
| multi-line function literals | -> <\n> <indent> a | Y |
| maths operators | /, +, -, %, * | Y |
| array literals | [a, b] | Y |
| explicit object literals | {a: b} | Y |
| {pre,post}fix {in,de}crement | --a, a--, ++a, a++ | Y |
| unary +/- | +a, -a | Y |
| explicit return | return 0 | Y |
| unconditional loop | loop then a | Y |
| break/continue | loop then break | Y |
| classes | class A | Y |
| class-extends | class A extends B | Y |
| class proto-assignments | class A then m: -> | Y |
| extends operator | A extends B | Y |
| switch-when-else | switch a <\n> when b then c | Y |
| try-catch | Y | |
| throw operator | throw a | Y |
| new operator | new A | Y |
| semicolons as seq operator | a; b | Y |
| string literals | “a” | Y |
| string hex escapes | “\x61” | Y |
| string character escapes | “\n” | Y |
| string line continuation | “<\n>a” | Y |
| regex literals | /a/ | Y |
| do operator | do a | Y |
| slices | a[b..c] a[b...c] | Y |
| unbounded slices | a[b...] a[..b] | Y |
| undefined -> void 0 | undefined | Y |
| null literal | null | Y |
| compound assignment | a <binary-op>= b | N |
| boolean aliases | yes/no/on/off | N |
| exponential notation | 1.2e+4 | N |
| bitwise operators | &/|/^/~/<</>>/>>> | N |
| soaked member access | a?.b | N |
| dynamic soaked member access | a?[b] | N |
| binary existential operator | a ? b | N |
| implicit function application | a b, c | N |
| proto-member access | a::b | N |
| dynamic proto-member access | a::[b] | N |
| @ as alias for this | @ | N |
| soaked function application | a?(b, c) | N |
| while loop | while a then b | N |
| postfix flow control | a if b, c until d | N |
| inclusive ranges | [a..b] | N |
| exclusive ranges | [a...b] | N |
| bound function literals | => | N |
| object key-omission shorthand | {a} | N |
| implicit object literals | a: b | N |
| (splat/rest)-params | (a...) -> | N |
| @-params | (@a) -> | N |
| named destructuring assignment | {a: b} = c | N |
| positional destructuring assignment | [a, b] = c | N |
| splat/spread arguments | fn a... | N |
| chained comparison | a < b < c | N |
| super | super | N |
| super with arguments | super a | N |
| external constructors | class A then constructor: c | N |
| try-catch-finally | N | |
| try-finally | N | |
| try | try a | N |
| typeof operator | typeof a | N |
| continue lines ending in binary operator | a and <\n> b | N |
| backslash continues lines | a \ <\n> + b | N |
| triple-quoted strings | “””<\n> a<\n>””” | N |
| heregexen | /// a /// | N |
| ACI in multiline array/object literals | [a<\n>b] | N |
| shallow copy of array | a[..] | N |
| splices | a[b..c] = d | N |
| unbounded splices | a[b...] = c | N |
| javascript literals | `javascript` | N |
| block comments | ### comment ### | N |
| default parameters | (a = b) -> | N |